Even some of the party’s leaders — from the lieutenant governor to a former speaker of the Missouri House — are openly discussing the idea of purging these lawmakers from the GOP.

“What we saw (on the right-to-work vote) were elected officials who used the surging Republican brand to get elected, but caved to union interests and lobbyist promises out of fear and self-preservation,” Lt. Gov. Peter Kinder said in a widely circulated column.

Kidd, who voted against the bill when it originally passed in May, so far isn’t among the targets of the first wave of ads.

His district — which covers parts of eastern Independence as well as Sugar Creek and Buckner — was a longtime Democratic stronghold before it was won by a Republican in 2010. A Democrat reclaimed the seat in 2012, but Kidd knocked him off to win the seat back in the Republican landslide year of 2014.

He insists his right-to-work vote was him listening to his constituents.

“My title is ‘representative,’ so I have to represent the people who are in my district. So that’s what I did,” Kidd said. “If I don’t get re-elected, that’s OK, too.”

But that argument has done nothing to quiet those who say a legislature with massive Republican majorities shouldn’t have a problem implementing a law coveted by conservative activists.

“The level of frustration from the grassroots conservative Republicans around the state is palpable,” said Ryan Johnson, president of the conservative nonprofit Missouri Alliance for Freedom. “I can’t tell you how often I hear, ‘What is the good of having a vetoproof majority if we can’t use it?’”

Rep. Bryan Spencer, a St. Charles County Republican who supported the bill, said he also felt the pressure.

“For the people who are using the tactics to get you to change your vote, threatening me doesn’t work,” he said.

Tim Jones helped build the 116-member Republican supermajority in the Missouri House during his tenure as majority leader and House speaker. He now serves as chairman of Missouri Club for Growth, and says it’s time for not just a Republican supermajority, but a conservative supermajority.

“We’re willing to lend a hand to help properly vet candidates and see if we can find out what they’re going to do when they’re under fire in the heat of the moment and forced to take a hard vote,” he said.

Voting against right-to-work was not easy, said Rep. Sheila Solon, a Blue Springs Republican. But, she said, it’s what her constituents wanted her to do. And one vote, she said, shouldn’t mean she gets cast out of her party.

“The 20 Republicans who voted ‘no’ on right-to-work are all great public servants,” Solon said. “They are conservative Republicans who vote for tax cuts, school choice, protecting our Second Amendment rights and who are strongly pro-life. Are they any less Republican because of one vote where they voted for their districts and did what the residents elected them to do, to be their voice in Jefferson City?”

In the end, the Sinquefield-funded primary challengers all fell short. But Johnson said a lesson was learned: Before you throw campaign funds at a race, you have to find the right candidate.

“It doesn’t matter how much money you have,” he said. “Candidate recruitment is key.”

Perhaps just like the tax cut, Johnson said, lawmakers can return in January and find a version of right-to-work that could win a vetoproof majority.

But even if that happens, he said, primary challenges are still likely.

“Right-to-work was the straw that broke the camel’s back,” he said. “It’s a vehicle for the frustration of movement conservatives for not having seen their policy vision succeed since Republicans took over the legislature.”

For its part, the Missouri Republican Party doesn’t seem eager for the intraparty fight.

Republicans hold massive majorities in both the Missouri House and Senate, so it’s inevitable that there will be policy disagreements, said John Hancock, chairman of the state GOP.

Even though the state party and a majority of its members support right-to-work, Hancock said, that doesn’t mean there isn’t room in the GOP for those who don’t. And no one legislator is preventing Missouri from becoming the nation’s 26th right-to-work state.

It’s the governor, Hancock said, and capturing the governor’s mansion in 2016 should be the focus.

“For anybody that’s passionately committed to making Missouri a right-to-work state, money and energy would be better spent in the governor’s race next year than on individual legislative races,” Hancock said.

Kidd maintains that he was doing what he was sent to Jefferson City to do, and that’s represent the people who elected him.

“I went against my party, went against my caucus,” he said. “I went up against great big money. But I didn’t go up against my constituents.”